Glycol antifreeze mixtures



United States Patent GLYCOL ANT IFREEZE MIXTURES Edward 0. Ohlmann, BayCity, Mich., assignor to The Dow Chemical Company, Midland, M1ch., acorporation of Delaware No Drawing. Application May 23, 1955 7 SerialNo. 510,576

7 Claims. (Cl. 252--74) This invention relates to glycol anti-freezeconcentrates, and to aqueous solutions and dispersions thereof havingdecreased foaming properties.

The glycol anti-freeze concentrates of the present invention areparticularly adapted for admixture with Water for use as heat exchangemedia in the circulating systems of internal combustion engines,especially in the cooling systems of automobile engines, and in such useare substantially non-foaming.

The novel non-foaming concentrates within the scope of the inventioncomprise a major proportion of a glycol from the class consisting ofethylene glycol and propylene glycol, and mixtures thereof, togetherwitha small though efiective proportion of a foam suppressing productconsisting of tri(hydroxy-polyoxyalkylene) ethers of glycerol.

Suitable tri-(hydroxy-polyoxyalkylene) ethers of glycerol in accordancewith the invention are those in which the glycerol nucleus issubstituted by three hydroxy-polyoxyalkylene ether chains each of whichconsists of a polyoxypropylene ether portion adjacent to the glycerolnucleus and a hydroxy-polyoxyethylene portion remote therefrom.

These compounds are prepared by first condensing propylene oxide withglycerol to form an intermediate propylene oxide-glycerol condensationproduct characterized by having three hydroxy-polyoxypropylene chainsattached to the glycerol nucleus, one at the site of each glyceroloxygen atom. Condensation is carried out until at least 30, andpreferably from 40 to 80 parts by weight of propylene oxide are reactedper part by weight of glycerol. The intermediate propyleneoxide-glycerol co ndensation product is then reacted with ethyleneoxide, thereby etherifying each polyoxypropylene chain at the site ofthe terminal hydroxy group and building up a hy droxy-polyoxyethylenechain on each. This reaction is continued until from about 0.1 to about0.4 of a part by weight of ethylene oxide has been reacted per part byweight of the intermediate material. The glycerolalkylene oxidecondensation reaction is best carried out under substantiallymoisture-free conditions at an elevated temperature in the presence ofany of the usual condensation catalysts, an alkali metal hydroxide oralkoxide being preferred.

The products so prepared are, for the most part, a complex mixture oftri(hydroxy-polyoxyalkylene) ethers of glycerol in which the lengths ofthe hydroxy-polyoxyalkylene chains vary considerably from one moleculeto 2 wherein R is a glyceryl radical; the sum of x, x, and x" representsthe average number of oxypropylene groups in the, compounds of themixture; the sum of y, y, and y" represents the average number ofoxyethylene groups in the compounds .of the mixture; the values of x, x,x"1and y, y, and y' being such that there is an average of at another inthe mixture. In other words, a given product,

least 54, and preferably from 72 to 195 oxyalkylene groups per glycerylradical; and the values of x, x, and x" being such that there is anaverage of at least 48, and preferably at least 63 oxypropylene groupspresent constituting from about 66 to 89 mole percent of the totaloxyalkylene groups.

These polyoxyalkylene products are virtually non-volatile, water-whiteto amber liquids which are highly soluble in benzene and a wide varietyof liquid aromatic compounds. They are also soluble in aliphatic andcycloaliphatic solvents such as acetone, carbon tetrachloride, ethanol,cyclohexanol, and the like, but are only slightly soluble to insolublein water. These liquid products are stable in air, do not deposit gummyresidues on heating, and are not corrosive to metals. As'previouslystated, these compounds prevent foaming frequently encountered in thecirculation and mechanical mixing of aqueous glycol'solutions,especially heated solutions.

Within the limits of the reactant ratios hereinbefore set forth, theseproducts, viz. tri(hydroxy-polyoxyalkylene) ethers of glycerol, have forthe most part average molecular weights of from about 1700 to about 5000as calculated from the weight percent of hydroxyl (as determined byacetylation) and reckoning three free hy- Expressing this in anotherdroxyl groups per molecule. way, the average molecular Weight of theglycerol-polyoxypropylene portions of these products as determined byhydroxyl prior to oxyethylation should be; at least 1500, andispreferably in the range of from about 2200 to about 4000. Theviscosities of these products are usually greater than 250 centistokesat 100 F. and may exceed v800 centistokes at 100 F. A detaileddescription of these products, and of their manufacture and use, isgiven in application Serial No. 396,773, filed December 7, 1953 by M. E.Pruitt et al. 7

' In the non-foaming concentrates of the invention, the glycol componentusually constitutes greater than percent by weight thereof. Aspreviously stated, the glycol component may consist entirely ofmonoethylene glycol or of monopropylene glycol. The monoglycolcomponent' may also consist of a mixture of the monoglycols of ethyleneand'of propylene in any proportion whatever. In addition to themonoglycols, one or both of therdiglycols may also be present in theconcentrate in small proportions, usually'less than 10 percent byweight.

In addition to the glycol component, the anti-freeze concentrates of the.invention contain a minor proportion of less than IO'percent by weightof one of the aforesaid tri-(hydroxy-polyoxyalkylene) ethers of glycerolas an antifoam agent. Such a compound, or mixture of compounds, issurprisingly effective in exceedingly low concentrationsin suppressingfoaming of aqueous glycol anti-freeze compositions, e.g. thetri(hydroxy-polyoxyalkylene) ethers of glycerol may be eifectivelyemployed in concentrations as low as 0.001 weight percent based on theglycol component. Ordinarily, however, at least 0.01 percent of the saidtri(hydroxy-polyoxyalkylene) glycerol compound is used, best resultsbeing obtained with from 0.01 to 1.0 weight percent thereof based on theglycol component. p

. Upon admixing water with the novel anti-freeze concentrates inaccordance with the invention, a substantially non-foaming anti-freezecomposition, for use as a heat exchange media in automobile radiators isobtained, In

normal usage, the greater the proportion of the concen- Patented Feb. 2,1960,

Isa- An tr'ate to water, the lower the freezing point of the resultantradiator liquid. Thus, an aqueous anti-freeze composition containing 30percent by weight of the concentrate has a freezing point of about l5C., while a composition of 60 percent concentration freezes at about 50C. Ordinarily no greater than a 50 weight percent aqueous anti-freezecomposition freezing at about --35 C. is required for use in automobileradiators.

To render the above aqueous anti-freeze compositions substantiallynon-corrosive to automobile circulating systems, it has been foundhighly desirable to add a small amount of a corrosion inhibitor,potassium dibasic phosphate being particularly effective in such use inan amount in the range of from about 0.5 to 5.0 percent by weight basedon the glycol. For good corrosion inhibition, about 2 percent K HPO(based on the glycol) is both a practical and effective amount toemploy.

It is also desirable to incorporate in the aqueous antifreezecomposition, a water-insoluble, Water-repellent material which will coatout on the internal surfaces of automotive cooling systems and preventleakage of the liquid coolant. A light mineral oil or petroleum fractionis suitable for such use, usually from 0.1 to 1.0 percent by weightbased on the glycol.

In preparing aqueous anti-freeze compositions in accordance with theinvention, an anti-freeze concentrate is first prepared and then dilutedwith water in an amount required to give the freezing point desired. Atypical anti-freeze concentrate, for example, is conveniently made up byfirst dissolving 2 parts by weight of K HPO in 2.4 parts water and thendissolving the resultant solution in 95 parts by weight of a glycolconsisting approximately of 90 percent of monoethylene glycol, balancediethylene and monopropylene glycols. To this phosphate containingglycol solution is then added 0.1 part by weight of one of the aforesaidtri-(hydroxy-polyoxyalkylene) ethers of glycerol, and 0.5 part of IndoilNo. 12, a light mineral oil. The anti-freeze concentrate so prepared,upon dilution with water, is a highly effective, substantiallynon-foaming anti-freeze composition for use in the cooling systems ofinternal combustion engines.

Example This example clearly illustrates the substantially nonfoamingcharacteristics of several aqueous glycol antifreeze compositionsaccording to the invention.

The aqueous glycol anti-freeze compositions employed in the followingtests were prepared by adding equal volumes of water to five diflferentanti-freeze concentrates consisting of different concentrations of thetrihydroxypolyoxyalkylene glycerol product as hereinafter describedadmixed with a glycol base material consisting approximately of 90weight percent monoethylene glycol, balance monopropylene and diethyleneglycols. The aforesaid trihydroxy-polyoxy-alkylene glycerol product wasprepared in accordance with the procedure set forth in the specificationby first reacting one part by weight of glycerol with approximately 65parts of 1,2-propylene oxide, and then reacting 0.20 part by weight ofethylene oxide per part of the intermediate glycerol-1,2-propylene oxidecondensation product. The average molecular weight of the intermediateglycerol-1,2-propylene oxide condensation product prior to oxyethylationwas greater than 3000 as determined by hydroxyl analysis.

The tests were carried out in a glass tube four feet in length and oneand five-eights inches inside diameter. The glass tube was fitted at itsbase with a medium porosity glass frit which was connected to anadjustable air supply line. A 200 ml. sample of the aqueous glycolanti-freeze composition to be tested was introduced into the glass tubeand air was passed through the glass frit and into the anti-freeze testcomposition at a rate such as to produce maximum foam. The results ofthe tests are expressed in inches of foam and are given in the '4following table opposite the concentrations of the foam suppressingtrihydroxy-polyoxyalkylene glycerol product. These concentrations aregiven in percent by weight based on the glycol base component of theanti-freeze concentrate prior to admixture with water.

'lrihydroxy-Polyoxyalkylene Glycerol Product,

Height, Inches That which is claimed is:

1. An anti-freeze concentrate consisting essentially of a majorproportion of a monoglycol from the class consisting of ethylene glycoland propylene glycol together with from .001 to 10 percent by weight ofa foam suppressing product consisting of a mixture oftri(hydroxypolyoxyalkylene) ethers of glycerol in which thepolyoxyalkylene ether chains consist of a polyoxy-1,2-propylene portionadjacent to the glycerol nucleus and a polyoxyethylene portion remotetherefrom, there being an average of from 54 to about oxyalkylene groupsper glycerol nucleus of which there are an average of at least 48oxy-1,2-propylene groups present constituting 66 to 89 mole percent ofthe total oxyalkylene groups.

2. An anti-freeze concentrate according to claim 1, the averagemolecular weight of the glycerol-polyoxy-1,2@ propylene portions of saidethers being at least 1500 as determined from the hydroxyl number.

3. An anti-freeze concentrate consisting essentially of a majorproportion of a monoglycol from the class consisting of ethylene glycoland propylene glycol and containing from .01 to 10 percent by weight ofa mixture of tri-(hydroxy-polyoxyalkylene) ethers of glycerol in whichthe polyoxyalkylene ether chains consist of a polyoxy- 1,2-propyleneportion adjacent to the glycerol nucleus and a polyoxyethylene portionremote therefrom, there being an average of from about 72 to 195oxyalkylene groups per glycerol nucleus of which there are an average ofat least 63 oxy-l,2-propylene groups present constituting from 66 to 89mole percent of the total oxyalkylene groups.

4. An anti-freeze concentrate according to claim 3, the averagemolecular weight of the glycerol polyoxy-1,2- propylene portions of saidethers being at least 2200 as determined from the hydroxyl number.

5. An aqueous anti-freeze composition consisting essentially of amixture of water and a monoglycol from the class consisting of ethyleneglycol and propylene glycol as the main constituents and containing inaddition thereto, from .01 to 10 percent by weight, based on themonoglycol, of a mixture of tri(hydroxy-polyoxyalkylene) ethers ofglycerol, said polyoxyalkylene compounds containing in their structureoxyethylene groups, oxypropylene groups, and a glyceryl radical, saidpolyoxyalkylene compounds being characterized in that the oxypropylenegroups are present in polyoxypropylene chains that are attached to theglyceryl radical, one polyox'ypropylene chain being attached to eachcarbon atom of the glyceryl radical, thereby constituting apolyoxypropylene glyceryl polymer portion, the oxyethylene groups beingpresent in hydroxy-polyoxyethylene chains, one hydroxy-polyoxyethylenechain being attached to the end of each polyoxypropylene chain, theaverage molecular weight of the polyoxypropylene glyceryl polymerportions in the compounds of the mixture being from 1500 to about 4000as determined by hydroxyl number, and the oxyethylene groups beingpresent in an amount equal to References Cited in the file of thispatent UNITED STATES PATENTS Van Horn ct a1 Oct. 27, 1953 Ohlmann Jan.5, 1954 Baird Mar. 9, 1954 Lundstcd Apr. 6, 1954 Jaccard Nov. 30, 1954Jursich Dec. 13,1955 Denman Dec. 20, 1955 Ryznar July 31, 1956

1. AN ANTI-FREEZE CONCENTRATE CONSISTING ESSENTIALLY OF A MAJORPROPORTION OF A MONOGLYCOL FROM THE CLASS CONSISTING OF ETHYLENE GLYCOLAND PROPYLENE GLYCOL TOGETHER WITH FROM .001 TO 10 PERCENT BY WEIGHT OFA FOAM SUPPRESSING PRODUCT CONSISTING OF A MIXTURE OFTRI(HYDROXYPOLYOXYALKYLENE) ETHERS OF GLYCEROL IN WHICH THEPOLYOXYALKYLENE ETHER CHAINS CONSIST OF A POLYOXY-1,2-PROPYLENE PORTIONADJACENT TO THE GLYCEROL NUCELUS AND A POLYOXYETHYLENE PORTION REMOTETHEREFROM, THERE BEING AN AVERAGE OF FROM 54 TO ABOUT 195 OXYALKYLENEGROUPS PER GLYCEROL NUCELUS OF WHICH THERE ARE AN AVERAGE OF AT LEAST 48OXY-1,2-PROPYLENE GROUPS PRESENT CONSTITUTING 66 TO 89 MOLE PERCENT OFTHE TOTAL OXYALYLENE GROUPS.